Can't serialize using DataContractSerializer - wcf

Question

I have tried the following code:
PolicyProcessRequest.BranchCode = "HeadOff"
PolicyProcessRequest.Policy.BranchCode = "HeadOff"
PolicyProcessRequest.Policy.Risks.Item(0).BranchCode = "HeadOff"
Dim dcs As DataContractSerializer = New DataContractSerializer(GetType(PureMessagingService.PolicyProcessRequestType))
Dim ms As New MemoryStream()
dcs.WriteObject(ms, PolicyProcessRequest)
Am getting the following exception on the call to WriteObject
System.Runtime.Serialization.SerializationException was caught
HResult=-2146233076 Message=Member BranchCode in type Sirius.SBO.Import.PureMessagingService.BaseRequestType cannot be serialized.
This exception is usually caused by trying to use a null value where a null value is not allowed.
The 'BranchCode' member is set to its default value (usually null or zero). The member's EmitDefault setting is 'false', indicating that the member should not be serialized.
However, the member's IsRequired setting is 'true', indicating that it must be serialized. This conflict cannot be resolved. Consider setting 'BranchCode' to a non-default value. Alternatively, you can change the EmitDefaultValue property on the DataMemberAttribute attribute to true, or changing the IsRequired property to false.
Yet I've set the 'BranchCode' property to the non default value everywhere in the request.
Public Class BaseNBQuoteRequestType
Private agentCodeField As String
Private branchCodeField As String
Private currencyCodeField As CurrencyType
Private currencyCodeFieldSpecified As Boolean
Private itemField As BasePartyType
Private policyField As BaseQuoteRiskMsgType
Private updatePartyField As Boolean
Public Property AgentCode() As String
Get
Return Me.agentCodeField
End Get
Set(ByVal value As String)
Me.agentCodeField = value
End Set
End Property
Public Property BranchCode() As String
Get
Return Me.branchCodeField
End Get
Set(ByVal value As String)
Me.branchCodeField = value
End Set
End Property
Public Property CurrencyCode() As CurrencyType
Get
Return Me.currencyCodeField
End Get
Set(ByVal value As CurrencyType)
Me.currencyCodeField = value
End Set
End Property
Public Property CurrencyCodeSpecified() As Boolean
Get
Return Me.currencyCodeFieldSpecified
End Get
Set(ByVal value As Boolean)
Me.currencyCodeFieldSpecified = value
End Set
End Property
Public Property Party() As BasePartyType
Get
Return Me.itemField
End Get
Set(ByVal value As BasePartyType)
Me.itemField = value
End Set
End Property
Public Property Policy() As BaseQuoteRiskMsgType
Get
Return Me.policyField
End Get
Set(ByVal value As BaseQuoteRiskMsgType)
Me.policyField = value
End Set
End Property
Public Property UpdateParty() As Boolean
Get
Return Me.updatePartyField
End Get
Set(ByVal value As Boolean)
Me.updatePartyField = value
End Set
End Property
End Class

Answer 1

I have the same problem, and it comes from the DataContractSerializer which is used to generate the code. I have other services which use the XmlSerializer with no problem.
Unfortunatly, when using Svcutil.exe or the 'Add Service Reference' feature in Visual Studio to generate client code, an appropriate serializer is automatically selected for you. If the schema is not compatible with the DataContractSerializer, the XmlSerializer is selected (source).
So, you have to manualy fix the IsRequired setting in references.cs each time you generate it.
Replace
IsRequired=true
by
IsRequired=false
in the references.cs file.